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P2A00








3MZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2A00: A/F Sensor Circuit Slow Response (Bank 1 Sensor 1)

DTC P2A00 - A/F Sensor Circuit Slow Response (Bank 1 Sensor 1)

DTC P2A03 - A/F Sensor Circuit Slow Response (Bank 2 Sensor 1)

DESCRIPTION

- DTC P2A00 indicates malfunctions related to the bank 1 air fuel ratio sensor.
- DTC P2A03 indicates malfunctions related to the bank 2 air fuel ratio sensor.
- Bank 1 refers to the bank that includes cylinder No. 1.
- Bank 2 refers to the bank that includes cylinder No. 2.
- Sensor 1 refers to the sensor mounted in front of the three-way catalytic converter and located near the engine assembly.

The air fuel ratio sensor generates voltage* that corresponds to the actual air-fuel ratio. This sensor voltage is used to provide the ECM (included in the hybrid vehicle vehicle control ECU) with feedback so that it can control the air-fuel ratio. The ECM determines the deviation from the stoichiometric air-fuel ratio level, and regulates the fuel injection time. If the air fuel ratio sensor malfunctions, the ECM is unable to control the air-fuel ratio accurately.
The air fuel ratio sensor is the planar type and is integrated with the heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), a current flows into the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are narrower than the conventional type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore the sensor activation is accelerated.
A three-way catalytic converter (TWC) is used in order to convert the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxides (NOx) into less harmful substances. To allow the TWC to function effectively, it is necessary to keep the air-fuel ratio of the engine near the stoichiometric air-fuel ratio.
*: Value changes inside the ECM. Since the air fuel ratio sensor is the current output element, a current is converted to a voltage inside the ECM. Any measurements taken at the air fuel ratio sensor or ECM connectors will show a constant voltage.









MONITOR DESCRIPTION

The output voltage of the air fuel ratio sensor varies in proportion to the air-fuel ratio. Based on these voltage variations, the ECM (included in the hybrid vehicle control ECU) determines whether the actual air-fuel ratio is rich or lean, and makes adjustments to bring it close to the stoichiometric level. In addition, the ECM checks the fuel injection volume compensation value to determine whether the air fuel ratio sensor response time is normal or slow. The ECM calculates the ratio of the variations in both air fuel ratio sensor output voltage and the fuel trim value.





MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

WIRING DIAGRAM





INSPECTION PROCEDURE
HINT: Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F sensor function provided in the Active Test. The Control the Injection Volume for A/F sensor function can help to determine whether the air-fuel ratio sensor, heated oxygen sensor and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the Control the Injection Volume for A/F sensor operation using the Techstream.
1. Connect the Techstream to the DLC3.
2. Put the engine in inspection mode Component Tests and General Diagnostics.
3. Start the engine and turn the Techstream ON.
4. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
5. On the Techstream, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F sensor.
6. Perform the Control the Injection Volume for A/F sensor operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
7. Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) displayed on the tester.
HINT:
- The Control the Injection Volume for A/F sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
- Each sensor reacts in accordance with increases in the fuel injection volume.

Standard:





NOTE: The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.





- Following the Control the Injection Volume for A/F sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.
- To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2, and press the graph button on the Data List View.
HINT:
- DTC P2A00 or P2A03 may also be set, when the air-fuel ratio is stuck rich or lean.
- A low air fuel ratio sensor voltage could be caused by a rich air-fuel mixture. Check for conditions that would cause the engine to run rich.
- A high air fuel ratio sensor voltage could be caused by a lean air-fuel mixture. Check for conditions that would cause the engine to run lean.
- Read freeze frame data using the Techstream. The ECM (included in the hybrid vehicle control ECU) records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

PROCEDURE

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2A00 AND/OR P2A03)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(e) Read the DTCs.
Result:





HINT: If any DTCs other than P2A00 or P2A03 are output, troubleshoot those DTCs first.

B -- GO TO DTC CHART Diagnostic Trouble Code Descriptions
A -- Continue to next step.
2. READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF A/F SENSOR)
(a) Connect the Techstream to the DLC3.
(b) Put the engine in inspection mode Component Tests and General Diagnostics.
(c) Start the engine.
(d) Turn the Techstream on.
(e) Warm up the air fuel ratio sensor at an engine speed of 2500 rpm for 90 seconds.
(f) On the Techstream, enter the following menus: Powertrain / Engine and ECT / Data List / A/F Control System / Snapshot / AFS B1S1 or AFS B2S1 and Engine Speed.
(g) Check the the A/F sensor voltage three times, when the engine is in each of the following conditions:
(1) While idling (check for at least 30 seconds)
(2) Fully depress the accelerator pedal and run the engine at 2500 rpm.
(3) Accelerator pedal released.
Standard voltage:










HINT:
- If the output voltage of the air fuel ratio sensor remains at approximately 3.3 V (see Malfunction Condition diagram) under any conditions, including those above, the air fuel ratio sensor may have an open circuit. (this will also happen if the air fuel ratio sensor heater has an open circuit.)
- If the output voltage of the air fuel ratio sensor remains at either approximately 3.8 V or more, or 2.8 V or less (see Malfunction Condition diagram) under any conditions, including those above, the air fuel ratio sensor may have a short circuit.
- The hybrid vehicle control ECU stops fuel injection (fuel cut) during engine deceleration. This causes a lean condition and results in a momentary increase in the air fuel ratio sensor output voltage.
- The hybrid vehicle control ECU must establish a closed throttle valve position learning value to perform fuel cut. If the battery terminal has been reconnected, the vehicle must be driven at over 10 mph (16 km/h) to allow the hybrid vehicle control ECU to learn the closed throttle valve position.
- When the vehicle is driven, the output voltage of the air fuel ratio sensor may be below 2.8 V during fuel enrichment. The vehicle translates this as a sudden increase in speed with the accelerator pedal fully depressed when trying to overtake another vehicle. The air fuel ratio sensor is functioning normally.
- The air fuel ratio sensor is a current output element; therefore, the current is converted into a voltage inside the hybrid vehicle control ECU. Measuring the voltage at the connectors of the air fuel ratio sensor or hybrid vehicle control ECU will show a constant voltage result.

NG -- INSPECT AIR FUEL RATIO SENSOR
OK -- Continue to next step.
3. PERFORM CONFIRMATION DRIVING PATTERN
NEXT -- Continue to next step.
4. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
(a) Read the DTCs using the Techstream.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Result:






B -- CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
A -- Continue to next step.
5. REPLACE AIR FUEL RATIO SENSOR
(a) Replace the air fuel ratio sensor Components.
NEXT -- Continue to next step.
6. PERFORM CONFIRMATION DRIVING PATTERN
NEXT -- Continue to next step.
7. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
(a) Read the DTCs using the Techstream.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Result:






B -- REPLACE HYBRID VEHICLE CONTROL ECU
A -- Continue to next step.
8. CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
(a) Has the vehicle run out of fuel in the past?.
NO -- CHECK FOR INTERMITTENT PROBLEMS
YES -- DTC CAUSED BY RUNNING OUT OF FUEL
9. INSPECT AIR FUEL RATIO SENSOR





(a) Disconnect the air fuel ratio sensor connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
Bank 1





Bank 2






(c) Reconnect the air fuel ratio sensor connector.
NG -- REPLACE AIR FUEL RATIO SENSOR
OK -- Continue to next step.
10. INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY
(a) Inspect the A/F relay Testing and Inspection.
NG -- REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY
OK -- Continue to next step.
11. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - HYBRID VEHICLE CONTROL ECU)





(a) Disconnect the air fuel ratio sensor connectors.
(b) Turn the power switch off.
(c) Disconnect the hybrid vehicle control ECU connector.
(d) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):






Standard resistance (Check for short):





(e) Reconnect the hybrid vehicle control ECU connector.
(f) Reconnect the air fuel ratio sensor connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
12. CHECK INTAKE SYSTEM
(a) Check the intake system for vacuum leaks.
OK:
No leakage from intake system.
NG -- REPAIR OR REPLACE INTAKE SYSTEM
OK -- Continue to next step.
13. CHECK PCV HOSE
OK:
PCV hose is connected correctly and is not damaged.
NG -- REPAIR OR REPLACE PCV HOSE
OK -- Continue to next step.
14. CHECK FUEL PRESSURE
(a) Check the fuel pressure Testing and Inspection.
NG -- REPAIR OR REPLACE FUEL SYSTEM
OK -- Continue to next step.
15. INSPECT FUEL INJECTOR ASSEMBLY
(a) Check the injector injection Testing and Inspection.
NG -- REPLACE FUEL INJECTOR ASSEMBLY
OK -- Continue to next step.
16. REPLACE AIR FUEL RATIO SENSOR
(a) Replace the air fuel ratio sensor Components.
NEXT -- Continue to next step.
17. PERFORM CONFIRMATION DRIVING PATTERN
NEXT -- Continue to next step.
18. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
(a) Read the DTCs using the Techstream.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Result:






B -- REPLACE HYBRID VEHICLE CONTROL ECU
A -- Continue to next step.
19. CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
(a) Has the vehicle run out of fuel in the past?.
NO -- CHECK FOR INTERMITTENT PROBLEMS
YES -- DTC CAUSED BY RUNNING OUT OF FUEL
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